Add test that basis implements vector interface

[blegat]

Needed to pass the tests of MultivariateBases but let me check why this is needed exactly.

Oops I missed #89
Closes #84
Closes #89

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 84.11%. Comparing base (fa145e1) to head (09b3d3e).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/bases_dirac.jl	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #90      +/-   ##
==========================================
- Coverage   84.15%   84.11%   -0.05%     
==========================================
  Files          15       15              
  Lines         871      875       +4     
==========================================
+ Hits          733      736       +3     
- Misses        138      139       +1     

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